4/30/2015 in Aircraft Accident Reconstruction … Tools in Aircraft Accident Reconstruction to Assist the ... validated with Aircraft Flight Manual ... view beyond the accident reconstruction

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New Tools in Aircraft Accident Reconstruction to Assist the Insurer

Steven L. “Steve” MorrisSenior Managing Consultant andManager of Colorado OperationsEngineering Systems Inc (ESI)

Overview

• ESI has reconstructed aircraft accidents since the company was founded in 1987

• Since then, we have participated in numerous aviation accident investigations both in and outside the U.S.

• Tape measures and cameras were essential accident reconstruction tools in 1987 and they are still very important tools today

• However, new powerful tools are now available and more are arriving every day

Overview

• X‐ray Computed Tomography (CT) of Parts

• Laser Scanning

• LiDAR

• New Aircraft Simulation Capabilities

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Overview


• Laser Scanning

• LiDAR


X‐rays

• Energetic, penetrating electromagnetic radiation

• Sensitive to electron density variations

• Higher Z, greater density materials – increased X‐ray attenuation

• Real time imaging possible

X‐rays

X‐ray source

Film or Detector

Sample

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Ejector Flow Valve X‐ray

X‐ray Limitations

• Image is a projection of everything intervening between the source and recording system (film or electronic detector)

• High density can obscure low density constituents

X‐ray Example

Consider 4 balls arranged in a box

How are they positioned in the box?

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X‐ray Example

?X‐ray source

X‐ray image

X‐ray Example

X‐ray source

X‐ray imagePossibility 1

X‐ray Example

X‐ray source


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X‐ray Example

X‐ray source


X‐ray image

All 3 result in the same X‐ray image

1 X‐ray image indeterminate for internal structure

X‐ray Example

X‐ray Example

?X‐ray source

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X‐ray Example

?

X‐ray source

X‐ray image

Correct Answer!

X‐ray image 1

X‐ray image 2MentalSudoku

X‐ray Example

Need even more imagesto completely determine ball locations

X‐ray CT

X‐ray

Computed

Tomography

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Intensity vs pixel position

Detector

Turntablewith sample

X‐ray source

X‐ray CT Technique



Detector


X‐ray source



Detector


X‐ray source

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From thousands of 2D X‐ray images, the computer reconstructs the sample in 3D revealing internal structure

Tomographic Reconstruction

Original Object CT Voxel Model

( x, y, z, ρe)

Tomographic Reconstruction

CT Scanning– 3D voxel computer model

• Orient and view in any direction

• “Slice” stacks of top, side, and front views

• Cut away and view internally (x, y, z, thresholding)

• View different material constituents (ρe thresholding)

– Dimensioning/metrology/CAD

– Advanced imaging and video capabilities

Industrial CT Scanning

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X‐ray source

Sample stage Detector


2‐D Linear

Detectors

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X‐Ray

CT

Ejector Flow Valve ‐ CT Image

Ejector Flow Valve ‐ CT Image

Valve Closed Valve Open

Altimeter

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Carburetor

Click on photo to play video

Carburetor Video

Click on photo to play video

Carburetor Video

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Project Example

Pitch Servo

Pitch Servo

Pitch Servo

Pitch Servo

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Pitch Servo

Capstan Gear

Pinion Gear

Capstan

Pitch Servo

X-ray source

2D detector

CT Scan of Pitch Servo

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CT Scan Slices of Pitch Servo

CapstanPinion Gear

Pitch Servo Disassembly

Contact marks on gear teeth

Pitch Servo Capstan Gear

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Contact marks on gear teeth

Contact marks



Contact marks “evidence” of gear train particle ingestion and binding

5 mm

Pitch Servo Pinion Gear

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Capstan Gear

Pinion Gear

CT Scan of Pitch Servo

Y_347

Capstan Gear

Pinion Gear

Y_682

122 μm = 0.0048 inch slices

Pitch Servo CT Slices

Y_347

Capstan Gear

Pinion Gear

Y_682

122 μm = 0.0048 inch slices


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Capstan Gear

Pinion Gear



Capstan Gear

Pinion Gear

Y_682

Subject Exemplar

Capstan Gear

Pinion Gear


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Capstan Gear

Pinion Gear

Contact Points

Pitch Servo Gear Interaction

Contact marks nothing more than marks imparted post‐accident with gears misaligned and partially

rotated likely during wreckage retrieval.

Summary

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Y_347

Pinion Gear engaged here

Pitch Servo Capstan Mount Plate

Y_347

Pinion Gear engaged here

Position at disassembly

Shadow from hole –position during post-crash fire


Overview


• Laser Scanning

• LiDAR


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Laser Scanning

• An extension of surveying equipment

• Provides a “cloud” of millions of points in color

• By moving the scanner to several locations but keeping the same reference points, a true 3‐D object is created

• You can view the “cloud” from any vantage point and get very accurate measurements

Laser Scanning

Laser Scanning

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Laser Scanning

Laser Scanning

• Has yet to be used on‐scene for an aircraft accident (to my knowledge)

• A laser scanning unit could be deployed and provide valuable information to every aircraft accident scene

• Excellent method for “preserving evidence”

– Can capture data/information that investigator does not immediately know is important

Laser Scanning

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Laser Scanning

Laser Scanning

Articulating Arm

Hard Contact Probe

Laser & Camera

Laser Scanning

Laser

Camera

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Laser Scanning

Laser Scanning

Laser

Camera

Camera Image

• Laser line projected over an object gives the profile of the object which is imaged by the camera

• Software renders a visual surface model

Laser Scanning ‐ Triangulation

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Laser Scanning – Point Cloud Data

Surface Deviation Map

Exemplar

Subject

Section Deviation Map

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Overview


• Laser Scanning

• LiDAR


LiDAR

• Light Detection And Ranging

• Optical remote sensing technology that can measure the distance to targets by illuminating the target with laser light and analyzing the backscattered light

• Highly accurate vertical measurements

• Can get a 3‐D digital image of an accident scene, regardless of the site’s remoteness

LiDAR

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LiDAR

LiDAR

LiDAR

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LiDAR

• Was recently used to document an aircraft accident scene

• Can provide VERY accurate 3‐D accident scene documentation

• Particularly useful for remote accident sites

• Can be very useful to subsequent accident reconstruction

LiDAR

Overview


• Laser Scanning

• LiDAR


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Simulations

• If animated, simulations help provide

– Visualization that posters cannot match

– 4‐dimensional (x, y, z, time) aspect to the understanding

– Understanding of the dynamic sequence of events in an accident

– More detailed reconstructions

Simulations

Simulations

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Simulations – Radar Data

Simulations – Reconstructed Data

6000

7000

8000

9000

10000

11000

0

50

100

150

200

250

20:40 20:41 20:42 20:43 20:44 20:45 20:46 20:47 20:48 20:49

Alt

itu

de,

ft

MS

L

Cal

ibra

ted

Air

spee

d, k

t

UTC

Altitude and Airspeed Histories

Airspeed

Altitude

Approximate Airspeed for Stall Warning Horn and Autopilot Disconnect

• Plaintiffs alleged that all three occupants were overcome by carbon monoxide poisoning and the plane entered a “hands‐off” spiral

• Could it be shown that the plaintiff’s spiral could not be flown without human input?

• J2 Aircraft Dynamics software provides a tool that can accurately relate the control deflections required to fly the flight path defined from the radar data

Simulations

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• Provides aircraft modeling and analysis

• Used to construct a reliable simulator model

• Simulator validated with Aircraft Flight Manual and/or Flight Test data

• Yields the control deflections required to fly a given flight path with tolerances

– provides insight on what the pilot was doing

J2 Dynamics Software


• Virtual function allows user to produce instant 3D animations of the reconstructed flight path with a graphic of the subject airplane and terrain map

• Data can be used to produce a high fidelity, courtroom quality animation


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Summary

• This has been a quick look at some of the tools that can be used in aircraft accident reconstruction

• Most of these tools came from other disciplines, so a broad view beyond the accident reconstruction community discipline is necessary

• Technology is changing rapidly – new tools continue to become available

Documents

4/30/2015 in Aircraft Accident Reconstruction … Tools in Aircraft Accident Reconstruction to Assist the ... validated with Aircraft Flight Manual ... view beyond the accident reconstruction